NAME

SYNOPSIS

DESCRIPTION

The sem_getvalue() function shall update the location referenced
by the sval argument to have the value of the
semaphore referenced by sem without affecting the state of the
semaphore. The updated value represents an actual semaphore
value that occurred at some unspecified time during the call, but
it need not be the actual value of the semaphore when it is
returned to the calling process.

If sem is locked, then the object to which sval points
shall either be set to zero or to a negative number whose
absolute value represents the number of processes waiting for the
semaphore at some unspecified time during the call.

RETURN VALUE

Upon successful completion, the sem_getvalue() function shall
return a value of zero. Otherwise, it shall return a value
of -1 and set errno to indicate the error.

ERRORS

The sem_getvalue() function shall fail if:

EINVAL

The sem argument does not refer to a valid semaphore.

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

The sem_getvalue() function is part of the Semaphores option
and need not be available on all implementations.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .